This invention relates to a method for inhibiting the temperature rise of a workpiece, typically a semiconductor body, when it is subjected to energy radiation in a vacuum particularly as is encountered in cathodic sputter etching.
In the fabrication of semiconductor devices, the selective removal of material from a surface by cathodic sputter etching causes the workpiece, which typically is a semiconductor wafer, to receive an energy flux in the form of electrons or ions or both. Inasmuch as a large fraction of this energy is dissipated as heat in the wafer, it is well known to take steps to inhibit the temperature rise of the wafer. Temperatures must be held at levels such that metallurgical and chemical interactions such as interdiffusion and recrystallization do not occur, inasmuch as such changes completely alter the semiconductor device structure.
Heretofore, insofar as applicants are aware, the art has resorted to cooling methods utilizing fluids, particularly water, arranged to be circulated adjacent mounting platforms for workpieces. In such arrangements, the workpiece is thermally coupled as intimately as possible to the cooling medium. A review of the patent art which discloses the use of circulating fluids for cooling indicates the cumbersomeness and complexity of such arrangements involving piping and coil arrangements as well as suitable clamping arrangements for the relatively fragile semiconductor wafer. The addition of such apparatus reduces the possibility of providing high throughput systems and obviously increases the cost.